The panel said in a report seen by AFP on Tuesday that sanctions against North Korea were "ineffective," with Pyongyang still able to acquire illegal shipments of oil products, sell banned coal and violate an arms embargo.

"The Democratic People's Republic of Korea's nuclear and ballistic missile programs remain intact," said the report, using the official name for North Korea.

"The panel found that the DPRK is using civilian facilities, including airports for ballistic missile assembly and testing with the goal of effectively preventing 'decapitation' strikes."

The confidential report was sent to the Security Council as President Donald Trump prepares for a second summit this month with leader Kim Jong Un that the United States hopes will yield concrete progress in dismantling Pyongyang's weapons programs.

The Trump administration has led the drive at the United Nations to impose a series of tough economic sanctions on North Korea in response to its nuclear tests and missile launches in 2017.

But North Korea has resorted to illegal transfers of oil, fuel and coal using a network of ships at sea to circumvent the UN-imposed measures aimed at depriving Pyongyang of revenue to build up its weapons programs.

"These violations render the latest United Nations sanctions ineffective by flouting the caps on the DPRK's import of petroleum products and crude oil as well as the coal ban imposed in 2017," said the report.

UN sanctions resolutions have set ceilings for North Korea of four million barrels of crude oil per year and 500,000 barrels of refined oil products.

- Rampant violations -

"The panel found that DPRK ports and airports are used for rampant violations of the resolution ranging from illegal oil imports and coal exports to the smuggling of bulk cash by DPRK nationals," said the report.

North Korea continues to violate an arms embargo and attempted to supply light weapons to Syria, the Huthi rebels in Yemen, Libya and Sudan, it added.

"Financial sanctions remain some of the most poorly implemented and actively evaded measures of the sanctions regime," said the panel.

North Korean financial institutions operate in at least five countries, despite UN-imposed restrictions, while the country's diplomats help their country evade sanctions by controlling bank accounts in multiple countries.

The panel's findings were in line with US intelligence assessments that North Korea is unlikely to scrap its weapons programs but may offer to scale back its activities to win sanctions relief.

Last week, US Director of National Intelligence Dan Coats said North Korea's leaders see nuclear weapons capability as "critical to regime survival."

US special envoy for North Korea Stephen Biegun will hold talks in Pyongyang on Wednesday to press for progress and steps that could be touted as success during the upcoming summit, which is likely to take place in Vietnam.